My personal opinion is that DL's configuration on the 767-400 is the best for space. Although the seat is not actually bigger, all seats have aisle access in the staggered layout and the space above the feet of the row behind is appreciated shoulder space. However most of their 767s still have the old business elite seats which are not as good. They are a bit narrow and not flat.

UA and CO's new seat are very similar. CO's seat is at an angle (seat does not face forward), so it isn't a true 2-1-2 configuration since the seat is a bit narrower since it is at an angle. The UA seat is staggered facing forwards and backwards which shrinks the foot space when in flat mode, but that is only a concern if you are taller.

In general if you want a good seat, take a DL 764 or UA 763 as they are the only fleets that have full flat products across their entire fleets. They are all big improvements over what the older seats are like. The two airlines with lower quality seats are AA and US. AA's angled flat seats aren't as good for sleeping, and the PTV is not built in. US has an old outdated product on the 767s.

If you have never designed an airplane part before, let the real designers do the work!

2-2-2 in the premium classes on 767s has always been a 2nd rate product with just one less seat across than in Y class. The best carriers were 5-abreast (referring to the old-style reclining seats), either 2-2-1, 2-1-2, or 1-2-2. For example, there was no cmparison between U.S. carriers' 2-2-2 layouts and AC/CP/CO/QF/AZ etc.with much more spacious 5-abreast configurations on longhaul 767s. The 6-abreast seats and armrests have to be narrower to fit while at 5-abreast you can use the same seats as on larger widebodies.

I always did my best to avoid carriers with 6-abreast business class layouts on 767s.